Problem: What do the following two equations represent? $-5x-5y = -5$ $-15x-15y = -15$
Answer: Putting the first equation in $y = mx + b$ form gives: $-5x-5y = -5$ $-5y = 5x-5$ $y = -1x + 1$ Putting the second equation in $y = mx + b$ form gives: $-15x-15y = -15$ $-15y = 15x-15$ $y = -1x + 1$ The above equations turn into the same equation, so they represent equal lines.